Pliny mentions that the best steel used in Rome was imported from China, a country in which copper or bronze swords are said to have been in use in the days of Ki,[86] the son of Yu, B.C. 2197-48, and those of iron under Kung-Kia, B.C. 1897-48, so that there also history points to a Bronze Age. But this by the way. Looking at the fact that iron and steel were in such general use at Rome during the period of her wars in Western Europe, we may well believe that had any of the tribes with which the Roman forces came in contact been armed with bronze, such an unusual circumstance could hardly have escaped record. In the Augustan age the iron swords of Noricum were in great repute, and farther north in Germany, though iron did not abound, it was, according to Tacitus, used for spears and swords. The Catti had the metal in abundance, but among the Aestii, on the right coast of the Baltic, it was scarce. The Cimbrians in the first century B.C. had, according to Plutarch,[87] iron breast-plates, javelins, and large swords. The Gauls of the North of France had in the time of Julius Cæsar[88] large iron mines which they worked by tunnelling; the bolts of their ships were made of that metal, and they had even chain cables of iron. The Britons of the South of England who were in such close communication with the opposite coast of Gaul must have had an equal acquaintance with iron. Cæsar mentions ingots or rings of iron as being used for money, and observes that iron is obtained on the sea-coast, but in small quantities, and adds that bronze was imported.[89] Strabo includes iron, as well as gold, silver, and corn, among the products of Britain. In Spain, as already mentioned, iron had long been known, so that from the concurrent testimony of several historians we may safely infer that in the time of Julius Cæsar, when this country was first exposed to Roman influences, it had already, like the neighbouring countries to the south, passed from the Bronze into the Iron Age.